Towed glider with automatic tow cable release



Sept. 30, 1952 R. M. CARLSON 2,612,327

TOWEID GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March 6. 1947 5Sheets-Sheet l I INVENTOR. I BY Russell M. Carlson ATTORNEY Sept. 30,1952 R. M. CARLSON 2,612,327

TOWED GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March a, 1947 I '5Sheets-Sheet 2 INVENTOR.

I BY Russell M. Carlson m Wm ATTORNEY Sept. 30, 1952 R. M. .CARLSON2,612,327

TOWED GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March 6, 1947 v v 5Sheets-Sheet 5 INVENTOR.

Russell M.- Carlson ATTORNEY Sept. 30, 1952 R. M. CARLSON 2,612,327

TOWED GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March 6, 1947 5Sheets-Sheet 4 Fig. 4

' INVHVTOR.

Russell M. Carlson RY ATTORNEY Sept. 30, 19 52 I R. M. CARLSON TOWEDGLIDER WITH AUTOMATIC ."lfOW CABLE- RELEASE w 1% m mm S V a WC m 0 w 4 Mh I H S e 5 m Filed March 6, 1947 7- f3. Fla

ATTORN Y Patented Sept. 30, 1 952 TOWED GLIDER WITH AUTOMATIC TOW CABLERELEASE Russell M. Carlson, Milford, Conn., assignor to United AircraftCorporation, East Hartford, Conn., a corporation of Delaware.

Application March 6, 1947, Serial No. 732,805

' This invention relates to towed gliders and has as one of its objectsthe provision of mechanism for automatically releasing the towing bridle.of a'towed glider upon ground contact following flight. I

Another object of the invention is the provision of mechanism of thistype which will enable the glider to be towed by the bridle duringtake-oif and which will automatically reset itself following take-off torelease the towing bridle upon ground contact following flight.

A further object of theinvention is the provision of tow releasemechanism operated by a ground contacting member and having air speedresponsive means for conditioning the mecha nism during flight forautomatic release by said member upon landing.

A further object of the invention is .generally to improve theconstruction and performance of towed gliders.

These and other objects and advantages of the invention will becomeapparent from the appended claims and from the following detaileddescription of the accompanying drawings which illustrate one embodimentof the invention.

In these drawings: 7 v

Fig. 1 is a perspective view of a towed glider embodying the inventionshown in flight;

Fig. 2 is a perspectiveview on an enlarged scale, with parts brokenaway, of apart of the automatic release mechanism;

Fig. 3 is a sectional view through this mechanism showing the parts inthe position which they occupy when the glider is on the ground readyfor take-off;

Fig. 4 is a similar view showing the. parts in the position they occupywhen the glider is in flight with the mechanism reset for automaticrelease upon ground contact and indicatin in broken lines the positionof the parts upon auto-v matic release of the bridle;

Fig. 5 is a section on line 55 of Fig. 3;

Fig. 6 is a section through an outboard fitting on a bridle post showingthe releasable connection for one end of the bridle; and

Fig. 7 is a modification showing an offset tow apparatus. v

As herein shown the towed glider, generally indicated in Fig. 1 by thenumeral It. comprises a long cylindrical fuselage I2 supporting twowings I4 and I6 located substantially mid-way 12 Claims. (01. 244-3) Thealightinggear comprisesvtwo main wheels I 26 and 28.mounted onlaterallyextended cantilever leaf springs 38 and 32 just aft of the mainwings I .4, l6 and a nose skid 34 carried by a hollow nose section 36 ofthe fuselage. Nose section 36 also supports the tow bar assemblies 22,24 each of which comprises identical, tubular bridle posts, or tow bars;38 ofstreamlined cross section, the outboard ends of which receive theshanks of fittings 48 and the. inboard ends of which have fittings 42rigidly secured in a .solid nose portion 44 of section 36. The'fittingsareof streamlined cross section extending'fore and aft thereof and are.supported by tension cables 46 extending inboard and aft therefrom tothe fuselage nose section 36 for the purpose of supporting the bridleposts against bending moments caused by a tow cable ,48' which isconnected to the glider by;

means of a V-bridle 50, the divergent aft ends of which are secured tofiat plates 52 which are received in slots, or kerfs, 54 extending foreand aft inthe end fittings 40. Each plate 52 is provided with a circularaperture-56 adjacent its aft end which registers with a transversepassage 58 in its fitting 40 in which a latch pin '60 is reciprocablebetween a, plate released position in which it is withdrawn from theaperture 56 in plate and a plate locking position in which it passesthroughthis aperture. I

The pins 60 are normally biased to locking position in which they enterinto apertures 56 and releasably hold the ends of the bridle 50-attached to the fittings 48. Tothis-end the inboard end of each passage58 in the shanks'of fittings 40 is provided withan enlarged portion 62to receive a compression spring 64 surrounding the pin 60 therein. Thespring acts at-one of'its ends against a transverse pin66 fixed in pin60 between the fore and aft ends of the fuselage,

the inboard end of the enlargedjportion 62.

Plates '68 have holes 18 therein through whichpins extend, and theinboard ends of pins 60 are fixed to cables 12 which extend inboardthrough tubularbars 38 into the hollownose section 36, a short length ofthe cables l2-beingexposed at the base of bridle posts 38 a's'is'shownmost clearly in Fig. 2.

The cables 12 from the .two latch pins 68 at the ends of bridle posts 38are identical and sym-- metrical with respect to thenose section 36-andare attached at their inboard ends to theopposite forward corners of arigid, generallyrectangular frame 14 pivoted intermediate its ends on atransverse bolt 16 which extends through the opposite side walls of thenose 560121011336, as'shown most clearly in Figs.,2 and 5. The aft endof 2,612,327 i 'i'" J;

The nose skid 34 is pivotally supported at its l o' forward end on a pin84 mounted in a rigid-v bracket 86 formed integral with the solid'noseportion 44 of nose section 36. At its aft end the skid is supported by ashock absorbing oleo strut} including an upper cylinder element 88having. an end fitting 90 and a cooperatinglower piston element 92having an end fitting 94'; A; pivot 96 carried by a pair of upstandingears v98 on skid 34 extends through fitting 94 tOIJiVOtELHIZ connectpiston element 92 with the skid. The oleo. strut extends freely upwardthrough an ample opening IBD in the bottom of nose section V 36 andhasits upper end fittingQfl pivotally mounted on aipin I02 which extendsbetween'the upper ends of two'parallel links I04, the lower ends ofwhich are 'pivotally supported between the sides of frame on bolt 16. Asuitable tubular spacer IllGis provided on the bolt I6 between the lowerends of links I04, and shorter but similar spacers. I08 are providedbetween the upper end of eachof these links and fitting 90 ofoleocylinder element (88. 1 r

Atone of itsends a compression sprin II!) abuts the .lower extremity ofcylinder. element 88 and at its "other end abuts pin 96 to constantlybiasthe elements 88 and 92 of the oleo strut into the fullyextendedposition thereof shown in Fig.

-4,'in which the parts are shown in theposition theyoccupyiustprior tolanding. An outstanding lug I I2 fixed to the upper end of cylinderelementBB and projecting aft of the latter has a flat upper face II4adapted to engage the lower end of the latch plate I! when the skid andattached oleo strut. areln theirlowermost' position as illustratedinthis figure, into which position .theyi'are biased lby= ravity when theairplane is off the ground; With the parts in the position shown in Fig,i it willbe evident thatengagementof skid 34 with the ground in landingwill result in the rotation of frame I4 counterclockwise," as indicatedby the arrow in this figure, and the withdrawalof locking pins 60 torelease the plates 52 at the ends of the bridle 50.

.JT-he oleo. will continue its upward movement intgtheDQSition shown inFig.3 in which it is 55 held .releasably by a latch I I6 carried byaspring loaded drag flap II'8 pivotally supported, at I20 on nosesection '36. Flap H8 is biased by a tori n Spring I22 into the elevatedposition shown in Fig. 3, thestrength of the springs being designed tomaintain the flap elevated until a predetermined airspeed has beenattained in flight, the spring I22 permitting the flap to move downward,as the fitting an on the upper end of the oleo in moving upward engagesthe latch I I6 and moves, back of the latter into engagement with a stopI24.

When in flight the selected airspeed has been reached which may be, forexample, 150 miles an hour. the flap. will be deflected downwardly 7against the, action of spring I22 sufficiently to move latch H6. out ofholding engagement with fitting 9|], of the oleo strut and permitthe-latter to move by gravity into. the Fig. 4 position in wmohathe lug;H2 is beneath latch plate '11; and;

the automatic release mechanism for the tow bridle 50 is reset.

In the position of the skid and its attached oleo strut when theairplane is on the ground, as shown in Fig. 3, the cylinder element 88of the oleo strut is fixed its fitting 99 being held against stop-124 i;nose-section 6=-byl1atch I IS with lug "Il2'well above tl'i'd'latchplate II so thatthe piston element of the strut is free to move into andout of cylinder 88 to absorb the landing energy in -compressionspring H0and the oleo strut in a ,usual manner. In operation, prior to making aflight the spring -loaded latch pins '60 will be withdrawn from the'kerfs 54in fittings 40 by pulling the cables I2 where'the latter areexposed near the base of the towabarsi-lfi. .This enables the plates '52on the ends of the bridle 50 to be inserted into the fittings Mendreleasably engaged by pins to.

As the glider stands on the ground prior to take-oif the oleo strutoccupies; the'po'sition shown iii-Fig; sun which its ntuhg e'o h agestlie'stop I24'Rand the lug "I12 'carried- 'by cylinder; 88 is asubstantial distance above latch Il on fr-ame 1 4. The flap H8 underthese conditions is biased by its sprin I 22 "into the -'el evated--po'sition of the flap shown in Fig.3 inwhich the latch l Iii for-m inga part thereofabuts the fitting '99 and prevents the latter :fror'nrnoving away from stop I24.

The parts will: remain in the Fig.3 position during take-off and.initial- 'fiightfuntil the airs speedis sufiicientito overcome the forceof spring I 22 and depress: the "flap 1 I8 a suffi'cient amount torelease theole'dstrut' from the'h'ol'd'ing eng agement' of latch. 1116.During 'take 'off' the oleo strut is free to operate? in its usualmanner to'absorb shocks in the event that the glider bounces but thecylinder element 88 thereofwhichi'carries the abutment H2v will.remain.'stationary relative to frame I4 and hence the bridlerelease-mechanism cannot operate; :When released the oleo strut and the;skid 3 1 :will' drop" by gravity into the Fig. l position which lug H2is-'beneaththe' latch plate IT, thus resettingithe l automatic bridlere-- lease mechanism. 1,

Upon landing, the initial engagement of nose skid 34With the ground willresult in movement of frame, min a counterclockwise direction about itspivot.16,,viewed=ih Fig. 4,:as cylinder 8:8 of the oleostrutuwhichcarrieslugIIZ moves; upward; As frame I4 reaches the'brokenline position shown in Fig. 4,,the. cables-l2 will have been .withdrawnsufi ciently 11in passages 5.8. to free. theplates 52 on the ends ofthe. tow bridletSIl', thus'releasing the glider from the towing plane.-As-1the oleo. strut continues. its upward movement. surface t I l of lugI12 moves away from latch plate H allow-' ing the frame I4 toresume itsnormal horizontal p ition this m v ment. being-,eifectedby thev force ofspringsfill which acting-through cables. 12 bias the frame constantly:into :the" normal position thereofrshdwnin-Figzfi;jand in: full lines nFig. 4. A-srvlfitting 9figalipmaiohesrstop; I24. it n a s. la ch. Hitandjdepresses thenaplis sufcien ly o ow; the fitting t more behind thislatch into the position shoWnIiI'LFi .;i3;,inJwhich the glider is readyfor another flight.

- n F 7; a-so ewhat modined'towappa atus s'heen -,sb.Q which p rmits:oni-setitowing of the l d r! I Inzthisl modificati n: the plate tfiinsteadofzbeing'fattached directly to: the Lends of the :y-brid e'jareprovided withpul'leysflze'over: which the ends .-.-t28.:"of tow-bridlet3lltrun. The ends. of thetow; bridles'are. connected by. aftran's-rversechain l32zwhichruns oyer-ardriving sproeket I34 mounted in the noseportion 44 on the splined end I36 of the shaft I38. It will be evidentthat rotation of shaft I38 in flight will shorten one end of the bridleI 30 while lengthening the other. Simultaneously with the rotation ofshaft I38, control surfaces I40 on the bridle posts 38 aredifferentially operated in such manner as to produce a side force theresultant of which lies along the axis about which the V-bridle I30rotates and the magnitude of which exactly balances the side forcesinduced by the bridle'so as to cause the glider to fly in an ofi-setposition relative to the towing airplane. The sprocket I34 is looselyreceived on the splined end I36 of shaft I38 so that a forward movementof the chain I32 will cause the sprocket to be pulled off the shaft. Thecable ends I28 and chain I32 run in tubular casings I42 one of which isin front of each bridle post 38 and is secured to the post by means of apair of clips I44 and I46.

It will be evident that upon release of the plates 52 as described inconnection with the construction of Figs. 1-6 the casings I42 will bepulled out of clips I44, I46 and the pulley I34 will be pulled off thesplined end I36 of the drive shaft I 38, thus releasing the glider fromthe bridle I30. During this releasing operation the bridle I 30 willoccupy a symmetrical position relative to the glider, automaticmechanism (not shown) being provided for controlling the rotation of theshaft I38 in response to movement of flap II8 so that upon a reductionof airspeed affecting this flap the glider will be restored to anin-line position with the towing plane. This off-set towing mechanismis. shown in detail and claimed in Patent No. 2,507,957 and reference ismade thereto for a more complete understanding of this mechanism.

It will be evident that as a result of this invention, mechanism hasbeen provided which enables a glider to be towed during take-off andwhich automatically resets itself following takeoff to enable the towingbridle to be released upon ground contact following flight.

It will be further evident that an automatic tow release mechanism hasbeen provided which is operated by a ground contacting member and whichhas airspeed responsive means for resetting the mechanism during flight.While two embodiments of the automatic tow release mechanism of thisinvention have been disclosed for purposes of illustration, it will beevident that various changesin the construction and arrangement of theparts may be made without departing from the inven-' tion as defined bythe following claims.

I claim:

I against which the glider connected end of said strut abuts, mechanismfor releasing said tow 1. A glider adapted to be towed by a powered Iairplane including, a ground engaging member, a tow bridle having areleasable connection to said glider, means for releasing saidconnection upon ground engagement of said member, means for disablingsaid releasing means during takeoff, and airspeed responsive meansincluding a flap pivoted to said glider and projecting into theairstream operative during flight for disabling said disabling means.

2. A glider adapted to be towed by a powered airplane including, a towbridle, means for releasably connecting said bridle to said glider,mechanism for operating said releasing means including a ground engagingmember on said glider, means conditioned when said glider is on theground including a latch for holding said mechanism in an inoperativeposition, and airspeed responsive means including a flap pivoted to saidglider and projecting into the airstream for movbridle connection havingan'operative connection with said strut in the fully extended positionof said landing gear, means for latching said landin gear with saidstrut engaging said stop, and airspeed responsive means controlling therelease of said latching means during flight for releasing said landinggear and resetting said releasing mechanism.

4. A glider adapted to be towed by a powered airplane including, aground engaging member having a lost motion connection with said gliderwhereby said member occupies one position relative to said glider whenthe latter is on the ground and a second position when the glider isairborne,

a tow bridle having a releasable connection to said glider, means forautomatically releasing said releasable connection as said member movesfrom said second position into said one position upon ground engagementof said member in landing, and airspeed responsive means including aflap pivotally supported on said glider and adapted to have the majorportion of its surface project into the airstream for latching saidmember in said one position during take-01f and for releasing the samefor movement to said other position to reset said releasing meansfollowing take-oil.

5. A glider adapted to be towed by a powered airplane including, a towbridle, means for releasably connecting said bridle to said glider,landing gear including a ground engaging member and an oleo strutconnecting said member with said glider, said strut and member adaptedto occupy an upper position when said member is in contact with theground and a lower position holding said landing gear in its upperposition,

and airspeed responsive means for releasing said latch and returningsaid landing gear to its lower position during flight.

6. A glider adapted to be towed by a powered airplane including, afuselage, main sustaining surfaces projecting laterally from saidfuselage intermediate the ends thereof, bridle posts projectinglaterally adjacent the forward end of said fuselage, a V'-bridle havingthe ends thereof releasably. connected to said bridle posts, means forreleasing said bridle ends including a pivoted member, a adjacent theforward end thereof, an oleo strut having its lower end pivoted to saidskid, link means having one end-pivoted to said fuselage and the otherend pivoted to the upper end of said strut, a stop for arresting theupward movement of said strut, a latch for holding said strut in itsupper position against said stop, and an airspeed responsive member formoving said latch out of strut holding position during flight, andcooperating means carried by said strut and said pivoted noseskid-pivoted to said fuselage '7 member for pivoting the latter as saidstrut moves upward upon engagement of said ground engaging member duringlanding.

'7. A glider adapted to be towed by a powered airplane including, atowbridle, mechanism for releasably connecting. said bridle to saidglider, landing gear including a ground engaging member and an oleostrutconnected at its opposite ends to said member and said glider, saidstrut having a lost motion connection with said glider, a stop againstwhich said glider connected end of saidstrut abuts when said member ison the ground, means for latching said landing gear with said oleo strutengaging said stop, airspeed responsive means controlling said latchingmeans, and means operated by ground engagement of said member in landingfor releasing said connecting mechanism as said oleo strut moves throughsaid lost motion into engagement with said stop.

8. .A glider adapted to be towed by a powered airplane including, afuselage having a nose portion, main sustaining surfaces extendedlaterally from said fuselage intermediate the ends thereof, bridle postsextended laterally from said nose section, a V-bridle having itsdivergent ends releasably connected to said posts, mechanism including apivoted member mounted in said nose section for effecting release ofsaid bridle connections, a nose skid having its forward end pivotallyconnected to said nose section, an oleo strut pivotally connected tosaid skid adjacent the aft end of the latter, a lost motion connectionbetween said strut and glider-including .link means having one endpivotally connected withsaid nose section and the other end pivotallyconnected with the upper end of said oleo strut,.abutment means forlimiting the upward movement of said oleostrut, a latch for holding saidstrut and skid in position in which said strut engages said abutment, .adrag flap responsive to a predetermined airspeed for moving said latchout of holding engagement whereby said strut is free'to extend,cooperating latch and abutment means, and one supported on said strutand the jother on "saidipivoted member for efiecting movement of thelatter to release said bridle upon upward movement of vsaid strut due toground engagement ofsaid skid.

9. ma glider adapted to be towed by-apowered airplane including, afuselage having a nosesection, a V-bridle, bridle posts extendedlaterally from said nose section having latch means at theirextremitiesproviding releasable connections for the divergent ends of said bridle,means1c'ontrolling the release of said connections including a pivotedelement, a groundengaging member, a strut connecting said member to the:glider having an operative connection with said pivoted element, meansfor releasing said'latchconnections upon ground engagement ofsaidimember in landing, and abutment means engaging said strut fordisabling said releasing means "during take-off.

10. A glider adapted to be towed bya powered airplane including, afuselage, :bridle posts extended laterally from said fuselageglatchmeansat'the'extremities of said posts, .latchengaging members'releasablyconnected to said posts by said :latch means, each having a pulleymounted thereon, a V-bridle having its divergent ends passing over saidpulleys, means for connecting said bridle ends, means carried by saidfuselage for laterally displacing said connecting means to off-set saidbridle, a ground engaging member,

and means operative upon ground engagement of said memberfollowing'fiight for actuating said latch means to release said latchengagin members.

11. A glider adapted to be towed by a powered airplane including, afuselage, bridle posts extendedon opposite sidesof said fuselage,tubular members disposed in front of said posts, means frictionallyconnecting said members to said posts, latch means at the extremitiesofsaid posts, latch engaging members releasably connected to said posts bysaid latch means, each having a pulley mounted thereonya V-bridle havingits divergent ends passing over said pulleys and extending intosaidtubular members, a drive shaft mounted in said fuselage having itsend projecting into the planeof said tubular members, a sprocket looselysplined .to the end of said shaft, a chain running over; said sprocketand connected to the ends of said bridle within said tubular members,means for driving said shaft to off-set said .bridle, a ground engagingmember, and means operative upon ground engagement of said groundengaging member following flight for actuating said latch means torelease said latch I engaging members.

12. In a glider adapted to be towed by a powered airplane including, afuselage having a nose section, bridle posts extended laterally fromsaid nose section having latch means at their eX- tremities, latchengaging members releasably connected to the ends of said posts by saidlatch means, each having a pulley, a V-bridle having its divergent endspassing over said pulleys, a chain between said pulleys connecting saidbridle ends, a fore and aft extended shaft having a driving endprojecting forward of said nose section, a sprocket loosely carried by.said shaft and operatively engaging said. chain, a ground engagingmember, and means operated upon ground engagement of said member forreleasing said bridle' including a pivoted member having operativeconnections with said member and said latch means.

' RUSSELL M. CARLSON.

' REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES .P ATENTS Great Britain Apr. 22, 1943 v

